Replaceable seat pocket assembly

ABSTRACT

A replaceable seat pocket assembly ( 10 ) for a gate valve body, the valve body comprises a recess ( 13 ) forming a seat pocket interface around the flow bore (B) by the gate opening, the seat pocket assembly ( 10 ) is arranged to be replaceable and comprises a ring shaped replaceable seat face ring ( 1 ), an energizing retaining collar ( 3 ) provided with threads. The invention also comprises a tool ( 1000 ) for replacing the replaceable seat pocket assembly, and also a kit and a method for installation of the replaceable seat pocket assembly.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.15/987,298, filed May 23, 2018 and entitled “Replaceable Seat PocketAssembly,” which is a bypass continuation of PCT Application No.PCT/IB2017/057195, filed Nov. 17, 2017, which is based on and claims thebenefit of priority from Norway Patent Application No. 20161861, filedon Nov. 23, 2016, each of which is incorporated by reference herein inits entirety for all purposes.

BACKGROUND

The purpose of a gate valve is to control the flow of production fluidsinto or out of a well. Gate valves can be operated in various ways suchas manually, hydraulically, pneumatically, and electrically. Alloperational models provide on-off flow control by aligning the gate,seat, and body flow bores (open) or aligning the solid part of the gatewith the seat and body flow bores (closed). The gate makes ametal-to-metal seal with the seat and the seat makes a metal-to-metaland/or elastomeric seal with the valve body. Gate valves typically havea floating seat that is not rigidly held in place and the seat iscaptured within the seat pocket that has traditionally been a featuremachined into the valve body. To operate the valve, the gate is moved upor down to either open or close the flow path.

Due to flow through the gate bore, movable parts, and operation of thevalve there will be wear around the valve seat and even break downs andthus need for expensive maintenance and repair of the valve.

The patent application US2003015681 describes a valve sealing assemblycomprising a first seat member (a pocket insert) and a second seatmember (seat), with rear sealing rings and exterior annular retainerrings. The retainer ring on the pocket insert retains the pocket insertin the valve body and the retainer ring on the seat retains the seat inthe pocket insert. The pocket insert comprises an exterior annulargroove arranged to accommodate the retainer ring. The retainer ring ismade of a flexible material, slightly oversized, to exert a force to thevalve body and retain the pocket insert in the valve body. The retainerring does not provide a seal but is preferably split to allow fluid flowaround the ring. The pocket insert has an L-shaped cross section andaccommodate the seat and make the interface between the seat and thevalve body. The use of elastomeric seals requires low energization andseat may be press fitted as is or press fit using a retaining collar.This is a disadvantage due to the risk that it may loosen unexpectedlycausing the system to be a seat, floating in a seat, floating in a seatpocket. Where “floating” is contained or captured but not rigidlyrestrained.

SUMMARY OF THE INVENTION

A main object of the present invention is to disclose a gate valveinsertion that solves the problems mentioned above, a tool forinstalling such an insert and a method for installation of the insert.The invention describes a kit for this.

The invention is a replaceable seat pocket assembly suitable for a gatevalve comprising a gate valve body, a flow bore, a gate opening, a gateand a gate cavity, the valve body comprises a recess forming areplaceable seat pocket interface around the flow bore by the gateopening, the recess having a rear wall and an inward facingcircumferential side wall with a threaded portion close to the gateopening;

-   -   the seat pocket assembly comprises    -   a replaceable seat face ring with a front and a reverse side, an        outer circumference wall and an inner circumference wall (100)

wherein the reverse side is for sealing arrangement to the rear wall andthe outer circumference wall is for tight fitting arrangement to theinward facing circumferential side wall,

-   -   an energizing retaining collar (ERC)

for arrangement onto an outer circumferential portion of the front ofthe replaceable seat face ring,

the energizing retaining collar having a threaded outer circumferentialwall to interact with the threaded portion,

-   -   the replaceable seat face ring and the energizing retaining        collar thus forming the replaceable seat pocket assembly for        arrangement as an interface between the valve seat and the gate        valve body.

Such a replaceable seat pocket facilitates an easy maintenance andrepair, just changing seat pocket insert instead of machining, welding,heat treating, and finish machining with carbon/low alloy, stainless, orCRAs. The repair will be much more cost and time efficient than for avalve without a replaceable seat pocket.

The retaining collar (3) and the seat face ring (1) provides a fixed butreplaceable seat pocket. Thus wear is limited to inside the replaceableseat pocket, with significantly reduced wear to the main valve body, isa resulting advantage. The use of a metal to metal seal energized by theERC is far more rigid and robust than a press fit cup design withelastomeric seals.

The invention is also a replaceable seat pocket assembly installationtool for a replaceable seat pocket, please see FIG. 11 and FIG. 12,comprising:

-   -   an extension rod and a torque key;    -   the extension rod having a first end arranged for engagement        with the torque key, and a second end with a bolt head such as        for a hydraulic torque tool;    -   the torque key being generally circular with a central        engagement slot for engagement with the first end, and two or        more arc-shaped load dogs on an outer circumference of the        torque key, the load dogs arranged for engagement with one or        more corresponding arc-shaped load slots in an energizing        retainer collar of the replaceable seat pocket assembly.

The invention also relates to a method for installing a replaceable seatpocket assembly in a gate valve comprising a gate valve body, a flowbore, a gate opening, a gate, a gate cavity, the valve body comprises aseat pocket interface recess forming a replaceable around the flow boreby the gate opening, the recess having a rear wall and an inward facingcircumferential side wall with a threaded portion close to the gateopening, please see FIG. 14;

operating through the gate cavity:

-   -   placing a seal ring into a groove in the rear wall of the        recess,    -   placing a ring shaped replaceable seat face ring with a front        and a reverse side (12), an outer circumference wall and an        inner circumference wall with the reverse side facing the seal        ring and the rear wall,    -   arranging an energizing retaining collar (ERC) onto an outer        circumferential portion of the front of the seat replaceable        face ring, by engaging a threaded outer circumferential wall of        the energizing retaining collar with the threaded portion in the        recess,    -   inserting a circular torque key with one or more arc-shaped load        dogs on its outer circumference and engaging the load dogs with        one or more corresponding arc-shaped load slots in the        energizing retainer collar, then

operating through the flow bore

-   -   inserting an extension rod through the flow bore, engaging a        first end of the extension rod into a central engagement slot of        the torque key and using a torque tool engaging a bolt head on a        second end of the extension rod and operating the hydraulic tool        and tighten to a required torque.

BRIEF DESCRIPTION OF THE DRAWINGS

The attached figures illustrate some embodiments of the claimedinvention:

FIG. 1a is section cut through a gate valve with a replaceable seatpocket, an RSP (1, 3), according to an embodiment of the invention.

FIG. 1b shows the detail indicated in FIG. 1 a.

FIG. 2a is section cut through a gate valve with a replaceable seatpocket (1, 3) according to another embodiment of the invention.

FIG. 2b shows the detail outlined in FIG. 2 a.

FIG. 3 is a combined section view and exploded view of the embodiment ofFIG. 1 a.

FIG. 4 is a longitudinal section view of a locking pin (21) forpreventing rotation of the replaceable seat pocket (1, 3).

FIG. 5 shows the embodiment as in FIG. 1a but with the gate (G) and seat(2) removed.

FIG. 6 is a section view and part elevation view of an embodiment of theseal ring (20). Here the illustrated section is cut through twothrough-holes (24) for the locking pins (21).

FIG. 7 is a detail section of the replaceable seat face ring (1) and theenergizing collar (3) according to the embodiment of FIG. 1a . the term“Energizing” is used for screwing in the collar (3) thus moving the seatface ring (1) inwardly to compress the seal ring (20), thus supplyingmechanical energy to the seal ring (20).

FIG. 8 is a detail section of the replaceable seat face ring (1) and theenergizing collar (3) according to embodiment of FIG. 2 a.

FIG. 9 is a section view of a gate valve with a replaceable seat pocket(1, 3) according to an embodiment of the invention. The gate (G) and theseat (2) are not shown. The right portion of the drawing is enlargeddetail D from the overview section in the left portion of the sheet.

FIG. 10 is a section view of a traditional gate valve (Prior art). Theupper illustration is a gate valve in an open position, and in the lowerillustration the gate and the seat are removed.

FIG. 11 is an embodiment of the invention, a replaceable seat pocketassembly installation tool (1000), here shown in an exploded view. Thering (1004) to the left shall engage with the energizing collar (3) forscrewing it in or unscrewing it.

FIG. 12 is an embodiment of a replaceable seat pocket assemblyinstallation tool (1000) in an assembled view as it will be assembledinside the valve body.

FIG. 13 shows a gate valve body portion, in a partly cut throughillustration and shows a replaceable seat pocket (1, 3) (RSP) accordingto an embodiment of the invention, in its installed position.

FIG. 14 is a similar illustration as FIG. 13 but with a replaceable seatpocket assembly installation tool (1000) according to an embodiment ofthe invention installed ready to be operated by an external torque tool.

FIG. 15 shows a Replaceable Seat Pocket system according to anembodiment of the invention with the Energizing Retaining Collar (3) andReplaceable Seat Face (1) shown installed in valve body cut in halfthrough the gate cavity (GC).

FIG. 16 shows an Energizing Retaining Collar (3) partly sectioned-off toshow its angled load planes (309) and similar Torque Key (1004) withangled load plane (1009) views. This ensures that the torque key (1004)will not slip out axially during torque loading.

FIG. 17a is a section view of a gate valve with a RSP according to anembodiment of the invention with design for a special designed seat,i.e. with chamfer for a flared seat. The seat is removed. The rightportion of the figure is enlarged detail D.

FIG. 17b is a section view of a gate valve with an RSP similar to FIG.17a with the special designed seat, i.e. with chamfer for the flaredseat (2) installed. The right portion of the figure is enlarged detailD.

FIG. 18a is a section view of a gate valve with an RSP according to anembodiment of the invention with another energizing retaining collar(ERC) design. The seat is removed. The right portion of the figure isenlarged detail D.

FIG. 18b is a section cut of a gate valve with an RSP similar to FIG.18a with an installed seat (2). The right portion of the figure isenlarged detail D.

EMBODIMENTS OF THE INVENTION

The invention will in the following be described and embodiments of theinvention will be explained with reference to the accompanying drawings.A precision machined metal ring (1) rigidly interfaces with the valvebody (0). The seat (2) facing side of the replaceable seat pocketassembly (1, 3) is precision machined smooth and flat, providing asealing surface, preferably metal, at least having the same sealingproperties to the seat pocket that is traditionally machined into thebody. The precision machined inside diameter of the retaining collar(ERC) (3) provides radial guidance for the floating seat (2). Togetherthese components completely replace the traditional seat pocket andprovide for a significant improvement to time and cost of repair. Morespecifically the invention is a replaceable seat pocket assembly (10)suitable for a gate valve comprising a gate valve body (0), a flow bore(B), a gate opening (GO), a gate (G) and a gate cavity (GC), said valvebody comprises a recess (13) forming a replaceable seat pocket interfacearound said flow bore (B) by said gate opening (GO), said recess (13)having a rear wall (131) and an inward facing circumferential side wall(130) with a threaded portion (132) close to the gate opening (GO);

-   -   said seat pocket assembly (10) comprises    -   a replaceable seat face ring (1) with a front (11) and a reverse        side (12), an outer circumference wall (101) and an inner        circumference wall (100)        wherein said reverse side (12) is for sealing arrangement to        said rear wall (131) and said outer circumference wall (101) is        for tight fitting arrangement to said inward facing        circumferential side wall (130),    -   an energizing retaining collar (ERC) (3) for arrangement onto an        outer circumferential portion of said front (11) of said        replaceable seat face ring (1),        said energizing retaining collar (3) having a threaded outer        circumferential wall (302) to interact with said threaded        portion (132);    -   said replaceable seat face ring (1) and said energizing        retaining collar (3) thus forming said replaceable seat pocket        assembly (10) for arrangement as an interface between a valve        seat (2) and said gate valve body (0).

The energizing retaining collar (3) will hold the replaceable seatpocket assembly (10) in place in the body (0). Please see FIGS. 1a and1b . Generally front sides are related to access and opening point whichfor a gate valve will be the gate opening. As seen from FIGS. 7 and 8the retaining collar (3) covers just a radially outer portion of thecircular front (11) of the seat face ring (1). Together, the inner wall(300) of the energizing retaining collar ERC (3), the front (11) and theinner wall (100) of the RSF will form what is usually called the seatpocket.

In this way the ordinary seat pocket, a machined cave in the valve bodyfor capturing the valve seat, is formed by two main features; a ringshaped replaceable seat face ring (RSF) (1) and an energizing retainingcollar (ERC) (3). Together they form a cavity inside the valve; thevalve seat pocket (10), for the valve seat (2), which is replaceable, areplaceable seat pocket, RSP (10). The seat will be retained floatinglyarranged, free to rotate inside the seat pocket and may be any generalseats for the purpose of a gate valve. The energizing retaining collarERC (3) is locked in place by threads (302) arranged to mate withthreads (132) in a portion of the valve body facing towards theenergizing retaining collar ERC (3), the replaceable seat pocketinterface (13). The threads are a cost effective way to assemble andcompress the two components. It provides and maintains, by torque andthrough the threads, the required large energizing forces and thethreads provide a rigidly restrained interface that will not allowfloating. (Thus called an energizing retaining collar.) Thusadvantageous above bolt squeezing, flange-like fixing of the replaceableseat face ring RSF(1)P and easier to operate than compressing with ahydraulic cylinder system and then lock in place by a final twist lock.

A gate valve for a replaceable seat pocket according to the inventionwill generally be manufactured to receive the replaceable seat pocket(1, 3). Which means it will be prepared with the special designedfeatures such as having a recess (13) forming the replaceable seatpocket interface around said flow bore (B) and being manufactured with athreaded portion (132) and other features for accommodation of differentportions of different embodiments of the replaceable seat pocket. Inanother aspect the replaceable seat pocket may be used for retrofitinstallations, which means that the valve body may post grinded and bythat prepared for the special designed features such as having a recess(13) forming the replaceable seat pocket interface around said flow bore(B) and with the threaded portion (132) and further features for theaccommodation of the different portions of the different embodiments ofthe replaceable seat pocket.

In an embodiment replaceable seat pocket arrangement according to theinvention, a seal ring (20), please see FIG. 1b , FIG. 2a , FIG. 3, FIG.6, FIG. 9, FIG. 14, is arranged between the replaceable seat face ring(1) and the rear wall (131) of said replaceable seat pocket interfacerecess (13). The replaceable seat pocket assembly (RSP) seals againstthe valve body with the seal ring (20) that is compressed, i.e.energized using the threads of the energizing retaining collar (ERC)(3). The energizing retaining collar (3) compresses the seal ring (20)between the ring-shaped replaceable seat face ring (RSF) (1) and thereplaceable seat pocket interface recess (13) and compresses/energizesthe seal ring (20) to prevent leakage. The valve body is alwayspressurized, during operation, i.e. in use, to upstream pressure. Thisseal ring provides a barrier against differential pressure and preventsflow between the replaceable seat pocket RSP (10) and the body. Floatinggate valves seal on the downstream side and so this prevents flow fromthe body cavity and downstream toward a flange.

The seal ring (20) will be a metal seal ring in an embodiment of theinvention. The use of a metal to metal seal energized by the ERC is farmore rigid and robust than a press fit cup design with elastomericseals.

For low pressure applications an elastomeric solution could work, butfor high pressurized systems a metal ring is favourable.

In a preferable embodiment when a metal seal ring (20) is used, the sealring is arranged in a cavity formed by opposite arranged ring shapedgrooves (16,19) at said reverse side (12) of the seat face (1) and therear wall (131) of said replaceable seat pocket interface recess (13)(respectively).

An embodiment of the replaceable seat pocket according to the inventioncomprises an anti-rotation lock (21, 18, 17) for said replaceable seatpocket (10). The anti-rotation lock prevents the seat pocket face ring(SPF) (1) and seal ring (20) from rotating and thus wear to seat,retaining collar and seat pocket. Actually it is also preventing gallingand other damage to the seal ring (20) and seal ring grooves ((16, 19)during installation.

In an embodiment the anti-rotation lock (21, 18, 17) comprises at leastone lock pin (21) arranged with a first end (22) in a hole (17) arrangedin said reverse side (12) of said seat face ring (1), and an oppositesecond end (23) in an opposite arranged retaining hole (18) in the rearwall (131) of the seat pocket interface recess (13). Advantageously,more than one lock pin (21) may be used, for example a number of four,evenly distributed in 90 degree angles of the circumference of the seatpocket, or there may be six, eight, or more lock pins The lock pin andhole system may be in an embodiment be replaced by a slot/key design butthis would not be as cost efficient as the pin system. Please see FIG.2b illustrating an embodiment with at least two lock pins arrangedcloser to the center of the ring shaped replaceable seat face ring RSF(1) aside of the ring seal.

An embodiment of the replaceable seat pocket according to the inventioncomprises a seat pocket interface (13) comprising at least one collarlanding rack/step (14) for the energizing collar (3) in the inwardfacing circumferential side wall (130) of said replaceable seat pocketinterface recess (13). This forms a step for thread clearance but theremay also be embodiments with a second step to allow for one or moretrash seals.

In an embodiment of the replaceable seat pocket (10) according to theinvention, the replaceable seat face ring (1) is made of metal, such assteel, stainless steel, or Inconel.

An embodiment of the invention having a seal ring (20) comprising atleast one through-hole (24) for said lock pin (21) and retaining holes(17,18) arranged within said ring shaped grooves (16,19). Please seeFIGS. 1b , 6 and 7. This means an embodiment where the pin anti-rotationlock system is through the seal ring (20) and its corresponding recesses(16, 19). The metal seal ring (20) cannot be allowed to rotate relativeto either of its mating parts. Anti-rotation pins in both thereplaceable seat face ring RSF (1) and the metal sealing ring (20)accomplishes this.

Putting the pins through the metal seal (20) reduces the space requiredin the body (0) and they will hold the seal (20) in place duringassembly.

In embodiments of the replaceable seat pocket the energizing retainingcollar (3) comprises one or more trash seals (304, 305) to an adjacentsurface as illustrated in FIG. 7, arranged in one or more correspondingrecesses of said energizing retainer collar (3). Such trash seals may bearranged in customized grooves in the energizing collar (3) surfacefacing towards the replaceable seat face ring or to the seat pocketinterface wall.

The seat (2) may also be arranged with a seal (200) between said seatand the replaceable seat (RSF) face ring (1). Please see FIGS. 1 and 3.A seat for use with the RSP may be off the shelf, but may also be one ofa special design for the RSP according to any embodiments of theinvention.

A general design of a gate valve will have symmetric designs which meansthat an embodiment according to the invention is arranged for flow ineither direction and comprises a replaceable seat pocket assembly (10)at both sides of said gate opening (GO).

In an embodiment of the replaceable seat pocket assembly the energizingretaining collar (3) comprises one or more load slots (307) forengagement with a torque key (1004) of replaceable seat pocket assemblyinstallation tool (1000), please see FIG. 12, FIG. 14, FIG. 16.

For installing or replacing the replaceable seat pocket RSP (1, 3, 10)according to the invention there was a need to develop a special toolwhich could apply a sufficient torque without risk of damage to theenergizing collar (3) or the tool or the valve body. Thus, in anotheraspect the invention also is a replaceable seat pocket assemblyinstallation tool (1000) for a replaceable seat pocket assembly (10)according to the first aspect of the invention and comprises anextension rod (1001) and a torque key (1004), wherein the extension rod(1001) having a first end (1001 a) arranged for engagement with thetorque key (1004), and a second end (1001 b) with a bolt head (1006) fora torque exerting tool such as a hydraulic torque tool, the torque key(1004) being generally circular with a central engagement slot (1007)for engagement with the first end (1001 a) of the extension rod, and twoor more arc-shaped load dogs (1008) on an outer circumference of thetorque key (1004), the load dogs (1008) arranged for engagement with oneor more corresponding arc-shaped load slots (307) in an energizingretainer collar (3) of the replaceable seat pocket assembly (10). Thetool (1000), Torque Tool, is not assembled before the valve is openedand the gate (G) removed from the gate cavity (GC) and the flow bore (B)opened. The torque key and the extension rod shall be assembled whenhaving been inserted through different paths of the valve body, i.e.through the gate cavity and the flow bore respectively.

The Torque Tool (1000) is used to energize the seal ring (3) by exertingtorque to tighten the energizing retaining collar (ERC) (3). This shouldadvantageously be done after the replaceable seat pocket assembly ismounted in place and hand tightened, then insert the torque key (1004)into the ERC (3) through the gate cavity (GC) and the extension rodthrough the bore (B).

The replaceable seat pocket assembly according to an embodiment of theinvention comprises one or more centralizing stabilizer guide discs(1003) for arrangement onto the extension rod (1001) and for stabilizingthe extension rod (1001) towards a wall (Bw) of the flow bore (B) in thegate valve body (0). One may achieve enough stability with a full-boretool with an extension rod (1001) with the same diameter as the flowbore of the valve, but this would be a rather unmanageable tool tohandle. It is important to stabilize the tool within the bore to ensurea correctly acting torque force and no skew force. After insertion ofthe torque key (1004), then, with the guide discs (1003) alreadyinstalled on the extension rod (1001), insert the extension rod (1001)into the flow bore (B) and engage the square drive (1001 b) of theextension rod (1001) with the square hole (1007) of the torque key(1004). Install one or more studs in the flange of the valve toanti-rotate the hydraulic tool. Tighten to the required to torque. Thetorque required may be very high in order to energize the seal (20).

In an embodiment of the invention the torque key has an engagement slot(1007) that is shaped as a square hole and the first end (1001 a) of theextension rod is a square drive. Embodiments having other than squaredesign may also be alternatives, the slot and pin may be “torque”,triangular, or hexagonal, or equivalent, while having sufficientlyrobust profiles for transferring the high torque required.

In an embodiment of replaceable seat pocket assembly installation toolthe load dogs (1008) has an angled load plane (1009) in at least one endof the arc-shaped load dog (1008) and a corresponding load plane (309)in the corresponding load slots (307) are angled correspondingly toreceive the load dogs (1008) and prevent slip out of the torque key(1004) when subject to torque. The required torque for energizing theseal (20) is extremely high (design max of 10000 ft-lbf [13558 Nm] sothe torque key (1004) and the energizing retaining collar (ERC) (3) havebeen designed with the angled load planes (1009) to pull the tool andring (3) together and prevent slip-out.

In an embodiment of the replaceable seat pocket assembly installationtool, the extension rod (1001) comprises ring shaped grooves (1013) forsplit retainer rings (1002) for the centralizing stabilizer guide discs(1003). This is an essential feature to have the guide discs reallycentralized and tight placed to prevent wiggling and skew.

An advantage of the centralizing stabilizer guide discs is that theextension rod (1001) is kept perfectly axially aligned in the flow bore(B) when subject to torque, so as for avoiding undesired deviation awayfrom the axially aligned position, which could otherwise damage thetorque key (1004) or incur damage to the replaceable seat pocketassembly or the bore or the gate valve body. Significant high torque isrequired to energize the seat pocket assembly.

The invention is also a replaceable seat pocket kit comprising aninstallation tool assembly (1000) according to the second aspect of theinvention and a replaceable seat pocket assembly (10) according to thefirst aspect of the invention.

The invention is also a method for installing a replaceable seat pocketassembly (10) in a gate valve comprising a gate valve body (0), a flowbore (B), a gate opening (GO), a gate (G), a gate cavity (GC), the valvebody comprises a seat pocket interface recess (13) forming a receptaclearound the flow bore (B) by the gate opening (GO), the recess (13)having a rear wall (131) and an inward facing circumferential side wall(130) with a threaded portion (132) close to the gate opening (GO),first operating through the gate cavity (GC), placing a seal ring (20)into a groove (19) in the rear wall (131) of the recess (13), placing aring shaped replaceable seat face ring (1) with a front (11) and areverse side (12), an outer circumference wall (101) and an innercircumference wall (100) with the reverse side (12) facing the seal ring(20) and the rear wall (131), arranging an energizing retaining collar(ERC) (3) onto an outer circumferential portion of the front (11) of theseat face ring (1), by engaging a threaded outer circumferential wall(302) of the energizing retaining collar (3) with the threaded portion(132) in the recess (13), inserting a circular torque key (1004) withone or more arc-shaped load dogs (1008) on its outer circumference andengaging the load dogs (1008) with one or more corresponding arc-shapedload slots (307) in the energizing retainer collar (3), then second,operating through the flow bore (B), inserting an extension rod (1001)through the flow bore (B), engaging a first end (1001 a) of theextension rod (1001) into a central engagement slot (1007) of the torquekey (1004) and using a torque tool (T) engaging a bolt head (1006) on asecond end (1001 b) of the extension rod (1001) and operating thehydraulic tool and tighten to a required torque. A torque tool (T) maybe a hydraulic tool or any tool capable of exerting a high torque on thebolt head (1006) in order to screw in the ring (3) and energize the sealring (20). The required torque for energizing the seal (20) is extremelyhigh (design max of 10000 ft-lbf [13558 Nm]).

We have described that we place the seal ring (20) into a groove (19) inthe rear wall (131) of the recess (13). We may also have a correspondinggroove (16) in the rear face (12) of the ring (2) to engage the sealring (20). We may also have only the groove (16) to retain the seal ring(20).

The method for removing the replaceable seat pocket is just the oppositesequence of the above method.

In an embodiment of the method according to the invention one will,ahead of the step of placing the ring shaped replaceable seat face ring(1) with a front (11) and a reverse side (12), an outer circumferencewall (101) and an inner circumference wall (100) with the reverse side(12) facing the seal ring (20) and the rear wall (131), insertanti-rotation pins (21) in retainer holes (18) in the rear wall (131),the anti-rotation pins (21) matching corresponding retainer holes (17)in the reverse side (12) of the replaceable seat face ring (1).

One may arrange the anti-rotation lock pins (21) through axial-parallelthrough-holes (24) in the seal ring (20). This will prevent both theseal ring (20) and the replaceable seat face ring (1) from rotating whenapplying torque to the system and prevent excessive shear forces on thesame. Thus, preventing undesired damage causing possible leakage etc.

Inserting lock pins (21) may be done ahead of placing the seal ring (20)into the groove (19) in order to place the seal ring and theanti-rotation pins in place at the same time and thus supporting theseal ring (20) before arranging the seat face ring (1). The specificsequence is up to the operator.

What is claimed is:
 1. A method for installing a replaceable seat pocketassembly comprising: working through a gate valve body to perform thefollowing steps: placing a replaceable seat face ring into said gatevalve body; arranging an energizing retaining collar onto said seat facering; inserting a torque key into said gate valve body and engaging saidtorque key with said energizing retainer collar; inserting an extensionrod into said gate valve body and engaging a first end of said extensionrod into said torque key and using a torque tool to engage a second endof said extension rod; and operating said torque tool to tighten to arequired torque.
 2. The installation method according to claim 1,wherein before the step of inserting the extension rod, arranging one ormore stabilizing guide discs onto said extension rod.
 3. Theinstallation method according to claim 1, wherein before the step ofplacing said replaceable seat face ring; inserting anti-rotation pins inretainer holes in said gate valve body, said anti-rotation pins matchingcorresponding retainer holes in said replaceable seat face ring.
 4. Theinstallation method according to claim 1, wherein the arranging stepfurther comprises: engaging a threaded outer circumferential wall ofsaid energizing retaining collar with a threaded portion in said gatevalve body.
 5. The installation method according to claim 1, whereinengaging said torque key with said energizing retaining collar furthercomprises engaging a portion of said torque key with a correspondingopening in said energizing retaining collar.
 6. The installation methodaccording to claim 1, wherein before the step of placing saidreplaceable seat face ring: placing a seal ring into said gate valvebody.
 7. The installation method according to claim 6, wherein beforethe step of placing said replaceable seat face ring; insertinganti-rotation pins in retainer holes in said gate valve body; andarranging said anti-rotation pins through axial parallel through holesin said seal ring; wherein said anti-rotation pins match correspondingretainer holes in said replaceable seat face ring.
 8. The installationmethod according to claim 6, wherein the step of placing the seal ringfurther comprises placing the seal ring into a rear wall of a recess ofsaid gate valve body.
 9. The installation method according to claim 8,wherein the step of placing the replaceable seat face ring furthercomprises placing the seat face ring adjacent said rear wall.